This application claims the priority of German Patent Document 198 20 921.5, filed May 9, 1998 and European Patent Application PCT EP99/02819 filed Apr. 27, 1999, the disclosures of which are expressly incorporated by reference herein.
The invention relates to a mobile transponder for a vehicle with a visual display.
Such a key is known from the DE 3740770 A. The visual display signals whether the vehicle is locked. However, it is often necessary to obtain information about the location of the vehicle. In this context it is known to provide a key of the vehicle with a voice storage, into which the location of the vehicle can be spoken (see DE 4309819 A). Relocating the vehicle is a function of whether this measure was actually performed, e.g. upon leaving the vehicle.
The invention is based on the problem of providing a mobile transponder for vehicles, whose visual display makes it possible to obtain an additional statement about the vehicle.
It is now possible with the aid of the visual display to recognize where the vehicle is located. An interrogation signal is transmitted over the antennas. The result is that the vehicle responds in the form of a radio signal. This response is evaluated in the transponder and displayed as visual information. Thus, it is absolutely possible with the directional characteristics of the antennas to detect the location of the vehicle with respect to its direction relative to the respective position and alignment of the transponder. This direction is signaled to the driver by an appropriate visual display.
The visual display can be designed as a small display, for example an LCD display. The direction, in which the vehicle is located with respect to the mobile transponder, can be presented as an arrow inside the display.
Correspondingly it is possible to show the directional information with the aid of light, for example LEDs (=light emitting diodes). They can be configured in a circle. The direction, in which the vehicle is located, can be determined with respect to the center point of the circle. Two diagonally opposite LEDs can also be activated. Thus the direction can be determined and indicated relatively. Frequently this information is adequate. Of the two directions that are thus possible, the driver has only to eliminate the direction opposite the actual direction.
In contrast, an improvement is a design that shows correctly and clearly the direction. One prerequisite is a corresponding directional characteristic of the antennas.
In another improvement of the invention the antennas determine not only the direction but also, in fact, the distance of the vehicle from the respective location. Thus, the vehicle user has the information, how far away the vehicle is from his respective location, where he and his mobile transponder are located.